Process of refining glycerin



Patented Nov. 8, 1949 UNITED STATES PATENT OFFICE PROCESS OF REFININGGLYCERIN tion of New Jersey No Drawing. Application August 15, 1947,Serial No. 768,925

Claims.

This invention relates in general to the purification of essentiallyanhydrous glycerine, and more particularly to a process for refiningessentially anhydrous glycerine obtained by the transesterification offatty materials.

From time immemorial, glycerine has been obtained chiefly as aby-product of the soap making industry, Conventional soap makingprocesses involve the saponification of suitable fatty materials with analkali such as sodium or potassium hydroxide. The reaction produces thealkali metal soaps of the fatty acids and glycerine. In the process ofseparating the soap from the reaction mass and purifying it,considerable quantities of water and common salt are utilized in theform of brine. Thus the glycerine resulting from the saponificationprocess ends up in a very dilute aqueous solution, which solutioncontains not only the glycerine but also considerable salt as Well asvarious impurities originally associated with the fatty material orresulting from side reactions during the saponification. In order toobtain a relatively pure, high quality glycerine from this impure,dilute aqueous solution, or spent soap-lye as it is commonly known,numerous involved processes have been proposed. Such processes not onlyadd to the cost of the final product, but also it is relativelydifficult to obtain good yields of anhydrous glycerine thereby. A partof this poor recovery of the glycerine is inherent in the saponificationprocess itself; however, a considerable amount of the loss is directlyattributable to the inefiiciency of the recovery processes.

In recent years it has been proposed to prepare esters of the fattyacids by reacting fatty materials with low molecular weight, monohydricalcohols such as methanol or ethanol in the presence of alkaline oracidic transesterification catalysts. These esters, after separationfrom the reaction mass and purification, may be used per se orsaponified to produce high quality soaps. The glycerine which resultsfrom such transesterification of glycerides is in an essentiallyanhydrous condition; however, the glycerine does have associated with itvarious impurities which were originally associated with the fattymaterial, were produced by side reactions during the transesterificationprocess, or were added to or produced in the reaction mixture incidentto the separais recommended that the glycerine obtained be diluted withwater before an attempt is made to purify it. Not only does this discardthe advantage of having obtained the glycerine in an anhydrous state,but also the addition of the water increases the solubility of certainof the impurities in the resulting glycerine solution thus in creasingthe difficulty of refining the glycerine as regards these impurities.

In the cop-ending application of Sprules and Price, Serial No. 761,160,filed July 15, 1947, there is disclosed an improved process forpreparing alkyl esters of the fatty acids involving firsttransesterifying fatty glyceride materials having acid values of atleast one with low molecular weight alcohols employing an alkalinematerial in sufficient quantity to neutralize the free fatty acids inthe fatty material, and provide sufficient alkaline material to serve asan alkaline catalyst, and then adding sulfuric or phosphoric acid to thereaction mixture in sufiicient amount to split What soaps werepreviously formed, neutralize the alkaline catalyst, and providesufficient acidic material to serve as an acid catalyst, and thereafteresterifying the free fatty acids in the mass with the alcohol therein.

It is the object of this invention to provide an improved process forrefining the crude, essentially anhydrous glycerine obtained by theSprules and Price process disclosed in the aboveidentified application.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

It has now been discovered that the foregoing and other objects of theinvention may be realized by reacting the acid catalyst after theesterification of the free fatty acids is completed, either with orwithout separating the acidic, crude anhydrous glycerine from thereaction mass, with an alkaline earth oxide or hydroxide, i. e. an oxideor hydroxide of calcium, barium, or strontium, subsequently treating thecrude anhydrous glycerine with a small amount of an ammonium halide byadmixing such a compound therewith, heating the mixture for a short timeand then removing any insoluble materials from the glycerine to recoveran excellent quality, anhydrous, refined glycerine. This refined andessentially anhydrous glycerine may be further purified, if desired, bydistillation, :codistillation with mineral oil, or by solventextraction, or by a combination of such further refining processes.

The manner in which our refining process brings about the desiredtransformation of the crude anhydrous glycerine to the ultimate re- 3fined product has not been definitely determined, but one possibleexplanation is as follows: Using the oxides MO, where M is barium,strontium or calcium, and assuming for purposes of illustration thatsome form of sodium has been employed as the alkaline catalyst and thatsulfuric acid has been employed as the acid catalyst, the sulfate in thecrude glycerine is converted into insoluble alkaline earth sulfate andan equimolar amount of sodium hydroxide is also formed according to thefollowing equation:

MO NaHSO M80 NaOH Any very small excess of sulfuric acid is converted tothe alkaline earth sulfate according to the following equation:

If the hydroxide is used, the following equations corresponding to theabove apply:

M(OH)2 NaHSO; MSO4 NaOH 11 In the last pair of equations much more wateris formed by the neutralization steps and for this reason the use of'theoxide is preferred.

In the second step of the refining process the ammonium halide (NH4X)neutralizes the sodium hydroxide which has been formed during the firststep of the process, and ammonia is liberated according to the followingequation:

In this manner, the residual acidic salts in the crude glycerine are allconverted to neutral salts which are insoluble in the glycerine and canbe removed by filtration.

The explanation of the manner in which the process may work appliesequally as well if the acid catalyst is phosphoric acid instead ofsulfuric acid or if an alkali metal compound other than a sodiumcompound is employed as the alkaline catalyst. The suggested mechanismfor the process is well borne out in practice, but we do not limitourselves to such an explanation.

Regardless of whether the above explanation is the proper one, we doknow that the refining process as set forth above, i. e. reaction of theacid catalyst with one of the basic compounds listed, followed bytreatment of the crude essentially anhydrous glycerine with a halidesalt as set forth and subsequent removal of insoluble materials from theglycerine-salt mixture, will produce an excellent grade of refinedessentially anhydrous glycerine much more simply and with greater yieldsthan previous refining processes. In view of the difficulties which havebeen encountered in the prior art in attempting to refine the glycerineobtained by transesterification processes, it is very likely that duringour refining process various chemical reactions take place in additionto the ones which we have outlined. Furthermore, the inorganic saltswhich we employ in our refining process undoubtedly exert variousphysical effects which aid in converting the various impurities in theglycerine into a form in which they may readily be separated from theglycerine. Thus it is quite apparent that the mechanism of our processis considerably more involved than the simplified explanation givenabove might indicate.

In the Sprules and Price process of producing the alkyl esters from thefatty materials through transesterification followed by esterification,some water is unavoidably produced whenever the alkaline catalyst whichis employed is one of the alkali metal hydroxides. The water is formedwhen the hydroxide is neutralized with either sulfuric or phosphoricacid preparatory to carrying out the esterification step of thatprocess; however, since the amount of alkaline catalyst which isemployed is quite small only a very small amount of water is produced bysuch neutralization. A. small amount of water is also produced by thechemical reactions involved in our refining process, but the amountproduced in that manner is also quite small. In fact the total amount ofWater produced by both the neutralization of the alkaline catalyst whensuch catalyst is an alkali metal hydroxide and by the reactions whichoccur in our refining process is so small that, comparatively speakingas regards such sources of water, the glycerine produced will berelatively Water-free.

If the fatty material being employed in the Sprules and Price processhas a relatively low acid value, .e. g. 10 or below, the amount of Waterproduced by neutralization of the free fatty acids prior to carrying outthe transesterification step of that process will be quite small.However, When the fatty material has a relatively high acid value, theamount of water produced by the neutralization of the free fatty acidswill be appreciable. Therefore, in order to obtain relatively anhydrousglycerine in such a case, it is preferred to carry out the Sprules andPrice process under conditions such that the water of reaction will becontinuously removed, e. g. by carrying out the process under refluxconditions and continuously separating the water from the alcohol beingemployed either by drying the alcohol-Water azeotrope over causticalkali, or by mechanically separating the water from the alcohol in aDean trap when the alcohol employed is one relatively immiscible withwater, or by any other suitable means. However, if desired, the Sprulesand Price process may in all cases be carried out under conditions suchthat the water of reaction will be continuously removed.

Any water left in the glycerine after the main steps of our refiningprocess will be removed for the most part when the glycerine is freed ofany of the alcohol used in producing the alkyl esters which is stillassociated with the glycerine. Also if the refined glycerine is itselfdistilled under reduced pressure so as to obtain a completely pureproduct, it may be completely freed during such distillation of anywater still associated therewith, and thus refined, completely anhydrousglycerine may be obtained.

In carrying out the process of the invention, the crude essentiallyanhydrous acidic glycerine is rst treated with a basic compound selectedfrom the group consisting of calcium hydroxide, barium hydroxide,strontium hydroxide, calcium oxide, barium oxide and strontium oxide.This treatment may be carried out on the entire reaction mass prior tothe removal of the essentially anhydrous glycerine therefrom, butpreferably the glycerine is first removed and then treated. After theessentially anhydrous glycerine has been so treated, either as a part ofthe esterification re action mixture or after separation from thereaction mixture, it may be filtered, if desired, to remove anyinsoluble material therein. If desired, the treated glycerine may beheated for a short time prior to such filtration since such heating willoften aid in converting the insoluble impurities therein into a formmore readily removable '5" by filtration. Such heating may convenientlybe carried out by heating the treated glycerine at about 60 C. or aboveby any convenient means, e. g. by a steam bath, for a short time, e. g.about half an hour.

The glycerine is then further treated by admixing therewith a smallamount of one of the halide compounds suitable for use in the secondstep of the refining process. If the first treatment with the metaloxides or hydroxides is carried out without separating the essentiallyanhydrous glycerine from the esterification reaction mass, such aseparation is made before adding the halide compound to the glycerine.In order to have a relatively fluid material to work with, it is usuallypreferred to allow a small amount of the alcohol employed in theesterification to remain with the glycerine during the refining. Notonly does it give a material which is easier to handle, but it alsohelps to prevent loss of glycerine due to adherence to filters duringfiltration. If, for some reason or other, all of the alcohol has beenseparated from the essentially anhydrous glycerine during the removalthereof from the esterification mixture, a suitable amount of theesterification alcohol or a similar alcohol may, if desired, be added tothe glycerine so that it will be less viscous. However, this is notnecessary and, if it is preferred, the process may be carried out onessentially anhydrous glycerine completely free of alcohol. Afteradmixture of the anhydrous glycerine and the halide compound, the massis heated for a short time. The heating may be carried out at anydesired temperature below that which would deleteriously affect theglycerine. A suitable temperature is from about 60 C' to about 120 C.When the glycerine being treated still has alcohol associated therewith,the heating may suitably be carried out in general at the refluxtemperature of the alcohol. The length of time of heating may varyconsiderably; however, heating for about half an hour to an hour will inmost cases bring about the desired degree of refining although the massmay be heated for a longer period, if desired. After the treatment withthe halide compound the glycerine is filtered to remove any insolublesalts and any other insoluble matter. The product obtained is a lightcolored, essentially anhydrous glycerine of good quality. If any alcoholis still admixed with the glycerine, it may readily be removed by asimple distillation.

The essentially anhydrous glycerine obtained by the process as describedhereinabove is of good quality, and for many purposes for which it maybe used, e. g. as a plasticizer, in adhesives, etc., no furthertreatment whatsoever is necessary; however, for some purposes it may bedesirable to refine the glycerine further. Occasionally the glycerinewill have a rather opaque or cloudy appearance or in some cases it mayeven be viscous or pasty. This is caused by the presence in theglycerine of small amounts of salts and other impurities which in somecases may be of such small particle size that it will sometimes bedifficult, if not impossible, to remove them by ordinary filtration. Ifit is desired to further refine the essentially anhydrous glycerine bydistillation thereof under reduced pressure, it is rather important toremove relatively large percentages of such impurities present prior tothe distillation since we have found that their presence during thedistillation may tend to decompose the glycerine thus reducing the finalyield and deleteriously affecting the quality of the prod not as some ofthe decomposition products distill 6. over with the glycerine giving itundesirable odors and colors as well as reducing the purity thereo Ifany difficulty is encountered in removing such impurities from theglycerine by filtration means, the impurities may be removed for themost part by contacting the essentially anhydrous glycerine containingthe impurities with a solvent selected from the group consisting ofmethanol, ethanol, propanol, butanol, and acetone. The extractionprocess should preferably be carried out at about room temperature or atemperature below room temperature, and in each extraction the ratio ofthe solvent to the essentially anhydrous glycerine containing theimpurities should preferably be from about 1 to 3 to about 1 to 7 inorder to obtain the best results. Under such conditions these solvents,which are immiscible with the impurities in the glycerine, will be foundto be somewhat immiscible with the essentially anhydrous glycerinecontaining the impurities but relatively miscible with glycerine whichis more or less free of such impurities. Thus when such a process iscarried out, the solvent will extract relatively pure, essentiallyanhydrous glycerine from the mixture of essentially anhydrous glycerineand impurities. By carrying out successive extractions, the essentiallyanhydrous glycerine may easily be separated from the greater part of theimpurities contained therein. When using acetone as the extractingsolvent, it will usually be necessary to carry out a greater number ofextractions than when employing the other solvents since acetone is nottoo miscible with glycerine. The essentially anhydrous glycerinecontaining the impurities may be contacted with the solvent in anydesired manner. A liquid-liquid extraction apparatus may be employed, orif desired a batch extraction process may be used with successiveportions of the solvent being contacted with the glycerine. By simplyfiltering the combined solvent extracts and removing the solvent therefrom, e. g. by distillation under reduced pressure, a fairly pure gradeof glycerine will be recovered. This essentially anhydrous glycerine maythen, if desired, be readily distilled without any decomposition to givein most cases a colorless, odorless, neutral, anhydrous glycerine ofsubstantially C. P. quality.

If any difficulty is experienced in separating the essentially anhydrousglycerine from the more or less colloidally sized impurities by means ofthe solvent extraction process as set forth in the previous paragraph,an alternate procedure may be employed. The essentially anhydrousglycerine mass may be completely dissolved in either methanol, ethanol,propanol, or butanol by employing an excess of the solvent. Acetone isthen added to the solvent solution until a precipitate of the impuritiesjust begins to form. Preferably an amount of the solvent just sufficientto cause the precipitate to redissolve is then added. The mass is thendigested by heating for a short time, e. g. by heating on a steam bathfor about half an hour at a temperature of about 50 to 60 C. or above.This treatment will cause practically all of the impurities which arestill associated with the essentially anhydrous glycerine to precipitateout, and they may then be readily removed from the glycerine byfiltration. After removal of the solvent from the solvent solution ofthe glycerine, the glycerine may be further purified by distilling itunder reduced pressure if desired.

In carrying out the distillation of the essentially anhydrous glycerineunder reduced pressure, the glycerine may be co-distilled with mineral0112a desired. Such a procedure will help prevent slight decompositionof the glycerine, and in some cases will help obtain a more nearlycomplete recovery of the refined glycerine. Any good grade of mineraloil having a boiling point temperature about the same or slightly higherthan that of glycerine may be utilized in such a co-distillationprocess.

Halide salts which are particularly suitable for use in the process ofour invention are ammonium chloride, ammonium fluoride and ammoniumbromide. Suitable mixtures of these salts may also be used if desired.Of these salts we prefer to employ ammonium chloride in view of thelower cost and ready availability of this compound.

The amount of ammonium halide which is employed in the halide salttreatment step of the invention is preferably determined by calculatingthe amount thereof which would be required to react with all of thesodium hydroxide, or other similar alkaline compound, present in theglycerine layer. We have found that such an amount of the ammoniumhalide gives very effective results in refining the essentiallyanhydrous glycerine.

After treating the reaction mass with either an alkaline earth hydroxideor oxide, and also after the halide treatment step of our process,insoluble materials may be separated from the glycerine by means otherthan filtration, for example by centrifugation, etc, if desired, as wellas by the solvent extraction processes described hereinabove.

For a fuller understanding of the nature and objects of the invention,reference may be had to the following examples which are given merely tofurther illustrate the invention and are not to be construed in alimiting sense.

Example I cooled somewhat, made acid with 20.2 parts of concentratedsulfuric acid and refluxed for an additional four hours. The reactionmixture was allowed to layer, and the lower glycerine layer was thendrawn off. To the glycerine layer there were then added 38 parts ofbarium oxide and the mixture was heated for one hour on a steam bath.The mixture was cooled and 29.5 parts of ammonium chloride were thenadded to it, and the mixture then heated for an hour on the steam bath.Most of the methanol associated with the glycerine was then removed bydistillation and the reaction mass filtered. The crude glycerineobtained was freed of methanol giving a somewhat viscous, cloudyproduct. Upon distillation of the crude glycerine under reducedpressure, an odorless, water-white, anhydrous glycerine having a pH of'7 was obtained in a yield of 83.7%.

Example II 900 parts of peanut oil having an acid value of one weretreated similarly as in Example I. In treating the glycerine layer,however, the barium oxide was replaced with 18.4 parts of calciumhydroxide. Also only 26.8 parts of ammonium chloride were used. Duringthe filtration of the crude glycerine following the ammonium chloridetreatment, a small amount of methanol was added to the glycerine toreduce its viscosity so that it could be filtered more easily. Uponremoval of all the methanol from the filtered glycerine, a cloudy, lightamber colcred product was obtained. Upon distillation of the glycerineat reduced pressure, an 85.5% yield of refined, anhydrous glycerine wasobtained.

Example III 904 parts, i. e. one mole, of peanut oil having an acidvalue of approximately one were transesterified by refluxing for onehour with 480 parts, i. e. 15 moles, of methanol, employing 9 parts ofsodium as an alkaline catalyst. 45.2 parts of sulfuric acid were thenadded and esterification carried out by refluxing for 4 hours. Aftercompletion of the esterification reaction, 38.0 parts of calciumhydroxide were added to the reaction mixture. The reaction mixture wasthen filtered, the excess alcohol removed, and the glycerine separatedfrom the esters. The crude glycerine was then heated with 15 parts ofammonium chloride at about 65 C. for approximately one hour. Any alcoholstill associated with the glycerine was then removed by distillation,the glycerine filtered and then vacuum distilled at 2 mm. Excellentquality anhydrous glycerine in an amount equivalent to 81% of thetheoretical yield was obtained.

Example IV 880 parts, i. e. one mole, of hydrogenated fish oil having anacid value of approximately two were transesterified by refluxing forone hour with 192 parts, i. e. six moles, of methanol, employing 8.8parts of sodium as an alkaline catalyst. 44 parts of sulfuric acid werethen added and esterification carried out by refluxing for four hours.After completion of the esterification reaction, 36 parts of calciumhydroxide were added to the reaction mixture. The reaction mixture wasthen filtered, the excess alcohol removed, and the glycerine separatedfrom the esters. The crude glycerine was then heated with 64 parts ofammonium chloride at about 65 C. for approximately one hour. Any alcoholstill associated with the glycerine was then removed by distillation,the glycerine filtered and then vacuum distilled at 2 mm. Excellentquality anhydrous glycerine in an amount equivalent to 75% of thetheoretical yield was obtained.

Our process is particularly applicable for the refining of essentiallyanhydrous glycerine but it is obvious, of course, that it is alsoapplicable to the refining of glycerine which is not essentiallyanhydrous. Consequently if it were de sired, the process could beemployed for refining crude glycerine obtained by thetransesterification of fatty material employing a combined alkali andacid'transesterification process even though such glycerine contained anappreciable amount of water. However, as has been pointed out above, thepresence of large amounts of water in the glycerine considerablycomplicates the refining process.

In the specification and claims when reference is made to neutralizingthe acidic glycerine or the acidic esterification mass with an alkalineearth oxide or hydroxide, the word neutralizing is used in the sensethat sufiicient of the alkaline earth compound is employed to completelyreact with all of the acidic material 'in the reaction mass. Thus theneutralized reaction mass will actually have an alkaline pH. The reasonfor this is that an alkali metal hydroxide (the alkali metal cationcoming from the alkaline catalyst employed in the transesterification)will be one of the end products of the reaction of the acidic materialwith the alkaline earth compound. It is true that there will be a pointat which the'glycerine or the esterification mass will have a neutralpH; however, the complete conversion of whatever alkali metal sulfate orphosphate is in the glycerine or in the esterification mass to thealkaline earth sulfate or phosphate necessarily produces a reactionmixture having an alkaline pH caused by the alkali metal hydroxideresulting from the neutralizing reaction.

Having described our invention what we claim as new and desire to secureby Letters Patent is:

1. In a process for refining glycerine obtained by transesterificationof a fatty material havin an acid value of at least one wherein thefatty material is transesterified employing an alkaline catalyst andthen esterfied employing an acid catalyst, the steps comprisingneutralizing the acidic glycerine with a compound selected from thegroup consisting of the alkaline earth hydroxides and oxides, heatingthe glycerine with an ammonium halide, and then Separating the glycerinefrom insoluble material formed therein.

2. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizing the acidic esterification mass with a compoundselected from the group consisting of the alkaline earth hydroxides andoxides, removing insoluble material formed therein from theesterification mass, separating th glycerine from the esterificationmass, heating the glycerine with an ammonium halide. and separating thetreated glycerine from insoluble material formed therein.

'3. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising separating the glycerine from the acidic esterification mass,neutralizing the acidic glycerine with a compound selected from thegroup consisting Of the alkaline earth hydroxides and oxides, heatingthe glycerine with an ammonium halide, and separating the treatedglycerine from insoluble material formed therein.

"4. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizing the acidic esterification mass with an alkalineearth hydroxide, removing insoluble material formed therein from theesterification mass, removing the majority of any excess unreactedalcohol from the esterification mass, separating the glycerine from theesterification mass, heating the glycerine with an ammonium halide, andseparating the treated glycerine from insoluble material formed therein.

5. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizing the acidic esterification mass with an alkalineearth hydroxide, heating the mass for a short time to aid in convertinginsoluble material in the mass into a more easily removable form,removing insoluble material formed therein from the esterification mass,removing the majority of any excess unreacted alcohol from theesterification mass, separating the glycerine from the esterificationmass, heating the glycerine with an ammonium halide, extracting thehalide treated glycerine at a temperature not above room temperaturewith a solvent selected from the group consisting of methanol, ethanol,propanol, butanol, and acetone, and recovering refined glycerine byremoving the solvent from the solvent extracts.

6. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizing the acidic esterification mass with an alkalineearth hydroxide, heating the mass for a short time to aid in convertinginsoluble material in the mass into a more easily removable form,removing insoluble material formed therein from the esterification mass,removing the majority of any excess unreacted alcohol from theesterification mass, separating the glycerine from the esterificationmass, heating the glycerine with an ammonium halide, dissolving thehalide treated glycerine in at least an equal weight of an aliphaticmonohydric alcohol containing not more than 4 carbon atoms, addingacetone to the alcoholic solution until a precipitate just begins toform, heating the solution for a short time, removing insoluble materialformed therein from the solution, and recovering refined glycerine byremoving the solvent from the solvent solution.

'7. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising separating the glycerine from the acidic esterification mass,neutralizing the acidic glycerine with a compound selected from thegroup consisting of the alkaline earth hydroxides and oxides. separatingthe glyc erine from insoluble material formed therein, heating theglycerine with an ammonium halide, extracting the halide treatedglycerine at a temperature not above about room temperature with asolvent selected from the group consis ing of methanol, ethanol,propanol, butanol, and acetone, and recovering refined glycerine byremoving the solvent from the solvent extracts.

8. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising separating the glycerine from the acidic esterification mass,neutralizing the acidic glycerine with a compound selected from thegroup consisting of the alkaline earth hydroxides and oxides, separatingthe glycerine from insoluble material formed therein, heating theglycerine with an ammonium halide, dissolving the halide treatedglycerine in at least an equal weight of an aliphatic monohydric alcoholcontaining not more than 4 carbon atoms,

adding acetone to the alcoholic solution until a precipitate just beginsto form, heating the solution-for a short time, removing insolublematerial formed therein from the solution, and recovering refinedglycerine by removing the' solvent from the solvent solution.

- 9. In a process for refining glycerine obtained by thetransesterification of. a fatty material having an acid value of atleast one wherein the fatty material is transesterified employing analkaline catalyst and then esterified employing an acid catalyst, thesteps comprising neutralizing the acidic esterification'mass with analkaline earth hydroxide, removing insoluble material formed thereinfrom the esterification mass, separating the glycerine from theesterification mass, heating the glycerine with ammonium chloride, andseparating the treated glycerine from insoluble material formed therein.

In a process for refining glycerine obtained by the transesterificationof a fatty material hav"- ing an acid value of at least one wherein thefatty material is transesterified employing an alkaline catalyst andthen esterified employing an acid catalyst, the steps comprisingseparating the glycerine from the acidic esterification mass,neutralizing the acidic glycerine with a compound selected from thegroup consisting of the alkaline earth hydroxides and oxides,heating'the glycerine with ammonium chloride, and separating the treatedglycerine from insoluble material formed therein.

11. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizin'g the acidic esterification mass with an alkalineearth hydroxide, removing insoluble material formed therein from theesterificati'on mass, removing the majority of any excess unreactedalcohol from the esterification mass, separating the glycerine from theesterification mass, heating the glycerine with ammonium chloride,separating the treated glycerine from insoluble material formed therein,and distilling the glycerine under reduced pressure.

12. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizing the acidic esterification mass with an alkalineearth hydroxide, heating the mass for a short time to aid in convertinginsoluble material in the mass into amore easily removable form,removing insoluble material formed therein from the esterification mass,removing the majority of any excess unreacted alcohol from theesterification mass, separating the glycerine from the esterificationmass, heating the glycerine with ammonium chloride, extracting theammonium chloride treated glycerine at a temperature not above aboutroom temperature with a solvent selected from the group consisting ofmethanol, ethanol, propanol, butanol, and acetone, recovering refinedglycerine by removing the solvent from the solvent solution, anddistilling the glycerine under reduced pressure.

13. In a process for refining glycerine obtained by thetransester-ification of a fatty material having an acid value of atleast onewherein the fatty material is transesterifled employing analkaline catalyst and then esterified employing an acid catalyst, thesteps comprising separating the glycerine from the acidic esterificationmass, neutralizing the acidic glycerine with a compound selected fromthe group consisting of the alkaline earth hydroxides andoxides,separating the glycerine from insoluble material formed therein, heatingthe glycerine with ammonium chloride, extracting the ammonium chloridetreated glycerine at a temperature not above about .room temperaturewith a solvent selected from the group consisting of methanol, ethanol,propanol, butanol, and acetone, recovering refined glycerine by removingthe solvent from the solvent solution. and distilling the glycerineunder reduced pressure.

.14. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizingthe acidic esterification mass with an alkalineearth hydroxide, heating the mass for a short time to aid in convertinginsoluble material in the mass into a more easily removable form,removing insoluble material formed there-- in from the esterificationmass, removing any excess unreacted alcohol. from the esterificationmass, separating the'glycerine from the esterification mass, heating theglycerine with ammonium chloride, dissolving the ammonium chloridetreated glycerine in at least an equal weight of an aliphatic monohydricalcohol containing not more than 4 carbon atoms, adding acetone to thealcoholic solution until a precipitate just begins to form, heating thesolution for a short time, removing insoluble material formed thereinfrom the solution, recovering refined glycerine by removing the solventfrom the solvent solution, and distilling the glycerine under reducedpressure.

15. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising neutralizing the acidic esterification mass with bariumhydroxide, removing insoluble material formed therein from theesterification mass, separating the glycerine from the alkyl esters,heating the glycerine with ammonium chloride, separating the treatedglycr erine from insoluble material formed therein, and

distilling the glycerine under reduced pressure.

16. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising separating the glycerine from the acidic esterification mass,neutralizing the acidic glycerine with barium hydroxide, separating theglycerine from insoluble material formed therein, heating the glycerinewith ammonium chloride, separating the treated glycerine from insolublematerial formed therein, and distilling the glycerine under reducedpressure.

17. In a process for refining glycerine obtained by thetransesterification of a fatty material having an acid value of at leastone wherein the fatty material is transesterified employing an alkalinecatalyst and then esterified employing an acid catalyst, the stepscomprising separating the glycerine from the acidic esterification mass,neutralizing the acidic glycerine with barium oxide, separating theglycerine from insoluble material formed therein, heating the glycerinewith ammonium chloride, separating the treated glycerine from insolublematerial formed therein, and distilling the glycerine under reducedpressure.

18. A process in accordance with claim 11 wherein the alkaline earthcompound which is employed is barium hydroxide.

19. A process in accordance with claim 12 wherein the alkaline earthcompound which is employed is barium hydroxide.

20. A process in accordance with claim 14 wherein the alkaline earthcompound which is employed is barium hydroxide.

FRANCIS J. SPRULES. RAYMOND LIEBLING.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

